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// Copyright (c) 2023-present, Raphael Amorim.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
//
// Compositor with vertex capture for text run caching
use crate::layout::{SpanStyleDecoration, UnderlineShape};
use crate::renderer::batch::{BatchManager, DrawCmd, QuadInstance, RunUnderline};
pub use crate::renderer::batch::{Rect, Vertex};
use crate::renderer::image_cache::glyph::GlyphCacheSession;
use crate::renderer::text::*;
pub struct Compositor {
pub batches: BatchManager,
}
impl Compositor {
pub fn new() -> Self {
Self {
batches: BatchManager::new(),
}
}
/// Creates an underline decoration based on the style and rect
pub fn create_underline_from_decoration(
&self,
style: &TextRunStyle,
) -> Option<RunUnderline> {
match style.decoration {
Some(SpanStyleDecoration::Underline(info)) => {
// Use font metrics for thickness when available, otherwise fall back to shape-based defaults
let underline_thickness = if style.underline_thickness > 0.0 {
style.underline_thickness
} else {
// Fallback thickness based on font size
// Use approximately 8% of font size for all underline types
let base_thickness = style.font_size * 0.08;
base_thickness.max(1.0)
};
// Use real font metrics for proper underline positioning
let underline_offset =
self.calculate_underline_offset(style, underline_thickness);
Some(RunUnderline {
enabled: true,
offset: underline_offset,
size: underline_thickness,
color: style.decoration_color.unwrap_or(style.color),
is_doubled: info.is_doubled,
shape: info.shape,
})
}
Some(SpanStyleDecoration::Strikethrough) => {
// Strikethrough should be positioned through the middle of the text
// Use font-provided strikeout_offset if available, otherwise x_height/2
let strikethrough_offset = if style.strikeout_offset != 0.0 {
// Font provides strikeout_offset as distance from baseline
-style.strikeout_offset
} else if style.x_height > 0.0 {
// x_height is the height of lowercase letters, strike through middle
-(style.x_height / 2.0)
} else {
// Fallback: 25% of ascent above baseline
-(style.ascent * 0.25)
};
// Use font metrics for thickness when available
let strikethrough_thickness = if style.underline_thickness > 0.0 {
style.underline_thickness
} else {
1.5
};
Some(RunUnderline {
enabled: true,
offset: strikethrough_offset,
size: strikethrough_thickness,
color: style.decoration_color.unwrap_or(style.color),
is_doubled: false,
shape: UnderlineShape::Regular,
})
}
_ => None,
}
}
/// Calculate underline offset using font metrics, with fallback
fn calculate_underline_offset(
&self,
style: &TextRunStyle,
underline_thickness: f32,
) -> f32 {
// Use font's built-in underline position when available
if style.underline_offset != 0.0 {
// Font provides underline_offset as distance from baseline to underline top
// Negative values mean below baseline, which is what we want
// But Rio's renderer expects positive offset for below baseline
-style.underline_offset
} else {
// Fallback: place underline 1 thickness below baseline
underline_thickness
}
}
#[inline]
pub fn finish(
&mut self,
instances: &mut Vec<QuadInstance>,
vertices: &mut Vec<Vertex>,
cmds: &mut Vec<DrawCmd>,
) {
self.batches.build_display_list(instances, vertices, cmds);
self.batches.reset();
}
/// Standard draw_run method (for compatibility)
#[inline]
pub fn draw_run(
&mut self,
session: &mut GlyphCacheSession,
rect: impl Into<Rect>,
depth: f32,
style: &TextRunStyle,
glyphs: &[Glyph],
order: u8,
) {
self.draw_run_internal(session, rect, depth, style, glyphs, order);
}
/// Internal rendering implementation
#[inline]
fn draw_run_internal(
&mut self,
session: &mut GlyphCacheSession,
rect: impl Into<Rect>,
depth: f32,
style: &TextRunStyle,
glyphs: &[Glyph],
order: u8,
) {
let rect = rect.into();
let underline = self.create_underline_from_decoration(style);
let subpx_bias = (0.125, 0.);
let color = style.color;
if let Some(builtin_character) = style.drawable_char {
if let Some(bg_color) = style.background_color {
let bg_rect =
Rect::new(rect.x, style.topline, rect.width, style.line_height);
self.batches.rect(&bg_rect, depth, &bg_color, 0);
}
if let Some(cursor) = style.cursor {
// Calculate cursor dimensions based on font metrics, not line height
let font_height = style.ascent + style.descent;
let cursor_top = style.baseline - style.ascent;
match cursor.kind {
crate::CursorKind::Block => {
let cursor_rect =
Rect::new(rect.x, cursor_top, rect.width, font_height);
self.batches.rect(
&cursor_rect,
depth,
&cursor.color,
cursor.order,
);
}
crate::CursorKind::HollowBlock => {
let outer_rect =
Rect::new(rect.x, cursor_top, rect.width, font_height);
self.batches.rect(
&outer_rect,
depth,
&cursor.color,
cursor.order,
);
if let Some(bg_color) = style.background_color {
let inner_rect = Rect::new(
rect.x + 1.0,
cursor_top + 1.0,
rect.width - 2.0,
font_height - 2.0,
);
self.batches.rect(
&inner_rect,
depth,
&bg_color,
cursor.order,
);
}
}
crate::CursorKind::Caret => {
let caret_rect = Rect::new(rect.x, cursor_top, 2.0, font_height);
self.batches.rect(
&caret_rect,
depth,
&cursor.color,
cursor.order,
);
}
crate::CursorKind::Underline => {
let caret_rect =
Rect::new(rect.x, style.baseline + 1.0, rect.width, 2.0);
self.batches.rect(
&caret_rect,
depth,
&cursor.color,
cursor.order,
);
}
}
}
if let Some(underline) = underline {
self.batches.draw_underline(
&underline,
rect.x,
rect.width,
style.baseline,
depth,
style.line_height,
);
}
self.batches.draw_drawable_character(
rect.x,
style.topline,
rect.width,
builtin_character,
color,
depth,
style.line_height,
0,
);
} else {
// Handle regular glyphs
for glyph in glyphs {
let entry = session.get(glyph.id);
if let Some(entry) = entry {
if let Some(img) = session.get_image(entry.image) {
let gx = (glyph.x + subpx_bias.0).floor() + entry.left as f32;
let gy = (glyph.y + subpx_bias.1).floor() - entry.top as f32;
// Scale PUA glyphs to fit constraint width
let glyph_rect =
if let Some((cell_w, cells)) = style.scale_constraint {
let target_w = cell_w * cells as f32;
let target_h = style.line_height;
let orig_w = entry.width as f32;
let orig_h = entry.height as f32;
// Fit proportionally within the target area
let scale =
(target_w / orig_w).min(target_h / orig_h).min(1.0);
let sw = orig_w * scale;
let sh = orig_h * scale;
// Center horizontally within constraint width
let cx = glyph.x + (target_w - sw) / 2.0;
// Align vertically from the baseline
let cy = gy + (orig_h - sh) / 2.0;
Rect::new(cx, cy, sw, sh)
} else {
Rect::new(gx, gy, entry.width as f32, entry.height as f32)
};
let coords = [img.min.0, img.min.1, img.max.0, img.max.1];
if entry.is_bitmap {
let bitmap_color = [1.0, 1.0, 1.0, 1.0];
// Get atlas index for this image (0-based), add 1 for layer (0 = no texture)
let atlas_layer = session
.get_atlas_index(entry.image)
.map(|idx| (idx + 1) as i32)
.unwrap_or(1);
self.batches.add_image_rect(
&glyph_rect,
depth,
&bitmap_color,
&coords,
atlas_layer,
);
} else {
self.batches.add_mask_rect_with_order(
&glyph_rect,
depth,
&color,
&coords,
true,
order,
);
}
}
}
}
if let Some(bg_color) = style.background_color {
let bg_rect =
Rect::new(rect.x, style.topline, rect.width, style.line_height);
self.batches.rect(&bg_rect, depth, &bg_color, 0);
}
if let Some(cursor) = style.cursor {
// Calculate cursor dimensions based on font metrics, not line height
let font_height = style.ascent + style.descent;
let cursor_top = style.baseline - style.ascent;
match cursor.kind {
crate::CursorKind::Block => {
let cursor_rect =
Rect::new(rect.x, cursor_top, rect.width, font_height);
self.batches.rect(
&cursor_rect,
depth,
&cursor.color,
cursor.order,
);
}
crate::CursorKind::HollowBlock => {
let outer_rect =
Rect::new(rect.x, cursor_top, rect.width, font_height);
self.batches.rect(
&outer_rect,
depth,
&cursor.color,
cursor.order,
);
if let Some(bg_color) = style.background_color {
let inner_rect = Rect::new(
rect.x + 1.0,
cursor_top + 1.0,
rect.width - 2.0,
font_height - 2.0,
);
self.batches.rect(
&inner_rect,
depth,
&bg_color,
cursor.order,
);
}
}
crate::CursorKind::Caret => {
let caret_rect = Rect::new(rect.x, cursor_top, 2.0, font_height);
self.batches.rect(
&caret_rect,
depth,
&cursor.color,
cursor.order,
);
}
crate::CursorKind::Underline => {
let caret_rect =
Rect::new(rect.x, style.baseline + 1.0, rect.width, 2.0);
self.batches.rect(
&caret_rect,
depth,
&cursor.color,
cursor.order,
);
}
}
}
if let Some(underline) = underline {
self.batches.draw_underline(
&underline,
rect.x,
rect.width,
style.baseline,
depth,
style.line_height,
);
}
}
}
}
impl Default for Compositor {
fn default() -> Self {
Self::new()
}
}